Drying apparatus and method of drying



July'29, 1941. e. OVERTON 2,250,773

DRYING APPARATUS AND METHOD OF DRYING Filed FeB. 4, 1939. 2 Sheet s-Sheet 1 Patented July 29, 19 41 UNITED, STATES PATENT OFFICE Glen Overton, Dowagiac, Mich. Application February 4, 1939, Serial No. 254,662

U 7' Claims.

This invention relates to drying apparatus and more particularly to a unit of drum driers for dehydrating liquid or pasty material in film form.

In accordancewith the principles of this invention, a pair of main drum driers are arranged to be dried into film form on the surfaces of the main drums and also to aid in the drying of the in adjustable surfacespaced relation with their axes substantially horizontal and auxiliary rolls which may be smaller than the main drum driers 1 are associated with the upper portionsof the main drums to serve in the distribution of the material to be dried over the surfaces of the main drums and also as auxiliary driers. Means are provided for independently heating the main and auxiliary drums so as to maintain temperature In order to facilitate further the formation of continuous, uniform films on the main drum driers, means are provided for driving the auxiliary rolls in the same surface direction as the main drums at the nips formed with the main drums but at a different and preferably a slower surface speed than that of the main drums. The rubbing action thus produced at the nips causes the films of material to be dried to adhere better to the faster rotating surfaces of the main drums and to spread out more uniformly.

Scraping means are provided in connection with each of the main drums to remove the film of dried material therefrom. Means also are material.

Other and further important objects of this\ invention will be apparent from the disclosures in the specification and the accompanying drawings. I V

This invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

0n the drawings: I

Figure 1 is an end elevational view of r a drying apparatus embodying the principles of my invention; t

Figure 2 is a top plan view;

Figure 3 is a view of a longitudinal section along the line III-III "in Figure 1, with parts in elevation; e

Figure 4 is a view of a transverse section along the line IV-IV in Figure 2.

As shown on the drawings: v

The reference numeral l0 indicates generally a pair of end housings provided with a pair of openings II and I2 through which extend the journals l3 and II of a pair of main drier drums i5 and I6, respectively. Said journals I3 and II are supported in bearing housings I1 and 18, respectively, mounted adjustably upon guideways l9 and 20. respectively. Adjusting screws 2| al ld 22 provide for individual adjustment of each g bearing housing II in the guideways I9, and

provided to-form, in cooperation with the auxiliary rolls, pockets on the upper surfaces of the main drums intowhich the material to be dried can be fed. This novel arrangement of drying apparatus facilitates the drying of relatively nonadherent liquid and pasty material and greatly increases the drying capacity over that of other types of individual drum driers heretofore used.

It is therefore an important object of this invention to provide an improved construction of drum drying apparatus for use in the drying of liquids and pasty materials that donot readily form adherent films ondrying surfaces.

It is a further important'object of this inven tion to provide a unit drier comprising a pair of main drier drums adjustable relative to each other to control the characteristics of the film of material being dried, and a pair of auxiliary rolls provided with independent heating means and with means for driving the rolls at a different surface speed from the drums, the rolls also being adjustable with respect to the surfaces of the main drums to serve in spreading the material similar adjusting screws 23 and .24 associated with each end bearing housing 18 permit adjust- "ment thereof to vary the spacing between the "as indicated at 25.. "Said drums I5 and ii are surfaces of said maindrier drums I5 and I6,

thus arranged with their axes in substantially the same horizontal plane and with their peripheries relatively adjustable with respect to eachother. n

An auxiliary roll 26 is mounted above the main drier drum 1 5 with its ends joumaled in a pair of bearing housings 21 supported from the end 'indicated by the reference numeral 31.

the geared wheel 66 and the geared wheel 6 Y.

mounted on the shaft of the drum l6.

For driving the rolls 26 and 3| suitably mounted geared wheels 1|] and 1| are provided which en- Y gage, respectively, the geared wheels 66 and 68. Geared wheels 12 and 13 are mounted, respectively, on the shafts of the rolls 26 and 3|. The geared wheels 10 and 12 engage each other, as do the geared wheels H and 13.

The ratio of the diameters of these geared wheels is so chosen that the rolls 26 and 3| are rotated at a slower surface speed than the drums l5 and I6. Preferably the surface speed of the drums l5 and l6-is from 10% to 40% greater than that of the rolls 26 and 3|. The direction of rotation of the surfaces of the drums I5 and I6 at the point indicated by 25 is downward.

A scraping member, blade or the like 36 is associated with the main drier drum |5 for removing the film of dried material formed thereon, Said scraper member 36 is secured upon a rod 39, which is pivotally mounted at its ends in bosses 48 formed on the end frames Adjusting mechanism for said scraper 36 comprises a pair terial 31 as it is scraped from the surface of the drum. Said trough 5| may be provided with a screw conveyor 52 for discharging the contents of the trough at one end thereof. A similar trough 53 and screw conveyor 54 is provided in association with the drier drum 5.

The drier drums I5 and I6 are provided with valve controlled steam pipes 55 and 56, respectively, and the auxiliary rolls 26 and 3| are provided with valve controlled steam pipes 51 and 5 8, respectively, by means of which said drums and rolls can be internally heated to the desired of stationary brackets 4| and adjusting bolts 42 threaded therethrough into a pair of brackets 38, which are securedto the rod 39. By adjustment of said bolts 42, the scraping member 36 is held under the desired pressure against the surface of the drum IS. A similar adjustable scraping mechanism, indicated generally by the reference numeral 43, is associated with the drier drum |6 for removing a film 44 of dried material from said drum.

A wooden board 95 is suitably mounted on the brackets 38 facing the roll 26. It conforms to and is held lightly against the surface of the drum |5 but extends past the ends of said drum to the outside of the end housings Ill. Upwardly the board 95 extends as high as the brackets 38. A similar board 96 is mounted in like manner facing the roll 3|.

A wooden board 16 is positioned perpendicularly to the drums l5 and i6 and the rolls 26 and 3| at one end thereof and another board 11 at the other end thereof. The shape of the wooden boards is such as to conform to the projecting shoulders "45, 46, 14 and 15. The wooden boards 16 and 11 reach upwardly to a line going through the center of the rolls 26 and 3|; downwardly to a line going through the center of the drums l5 and I6 and in the other directions so as to contact the boards 95'and 96. The wooden boards 16 and 11 are held lightly against the ends of the drums I5 and I6 and the rolls 26 and 3| by springs such as 18 and 19 mounted upon pins such as 80, 8|, 82 and 83 which project from the sides of the boards 'away from the drums and rolls into suitable apertures in the end housing l8.

Pockets 41 and 48 respectively, are formed betemperatures independently of each other.

A bar 84 slidably mounted in bearings 85 and 86 in the end housings l8 extends above and parallel to the pocket 41 at the level of the top of and a slight distance in front of the roll 26. The bar 84 is so long that approximately of its length projects outside the bearings 85 and 86. A similar bar 81 is mounted in like manner in bearings 88 and 89 in front of the roll 3|. A cross bar 98 connects the bars 84 and 81. The bars 84 and 81 may be ,moved backward and forward for a distance not exceeding about of their length by the reciprocating piston 9| connected with the cross bar 90. The piston 9| is activated by steam in the cylinder 92 supported from the housing ill by the bracket 93.

A plurality of rods 94 extend downwardly from the bars 84 and 81; they are bent so as to almost conform to the lower half of'the surface of the tween the respective rolls 26 and 3|, boards 95 j rolls 26 and 3| and are so long that they extend almost into the nips between the drums l5 and I6 and the rolls 26 and 3| The rods 94 are so spaced on the bars 84 and 81 that the back and forward movement of the latter will never carry any of the bars 94 beyond the ends of the drums I5 and I6.

It will be understood, however, that many details of the drying apparatus described as an example may be changed without departing from the principles of this invention. The driers II and I6 and the rolls 26 and 3| may, for instance, equally well be driven by a system of sprocket wheels and chains. The drums l5 and I6 and the rolls 26 and 3| may be heated directly by gas or oil flames. The bars 84 and. 81 may be caused to move back and forward by a spring at one end and a wheel rotating around a noncentral point actuating the other end. By a rearrangement of the scraping devices and the feeding of the material to be dried into the nip 25 between the main drier drums l5 and i6 the direction of rotation of said drums and rolls may be reversed from that shown. It is also possible to use different arrangements and different numbers of drums and rolls.

In operation, the drums l5 and Hi may be supplied with live steam at say lbs. per sq. in. and the auxiliary rolls 26 and 3| with steam at say 60 lbs. per sq. in. This gives a temperature differential between the surfaces of the drums and that of the heated rolls that tends to cause the material to be dried to adhere to the drum surfaces rather than to the roll surfaces." Under some circumstances, however, the rolls 26 and 3| may be run .cold. The speed of rotation 'of the drums and rolls will, of course, depend upon the drying properties of the matethese rolls, as well as the evaporated.

The material to be dried is fed into the pockets 4'! and 48 to provide .a constant supply of material at these points, as indicated by the reference numerals 49 and 50. The rods 94 moving back and forward through the accumulations 49 and 50 facilitate the escape of any bubbles of steam which may form in said accumulations and which might otherwise cause an unequal distribution on the surface of the drums I5 and I5 of material from said accumulations as the drums I5 and I5 revolve, in spite of the film forming action of the auxiliary rolls 25 and 3I.- The differential surface speed between the rolls and drums facilitates the adherence of the material to the drum surfaces in uniform contour. Some part of the material to be dried may, however, adhere to the surface of the rolls 26 and 3|. Such material will be returned to the accumulations 49 and 50 amount of'water to be This waste includes the'rlnd, cellular tissues and seeds of thegrapefruit. In its form as discharged from fruit juice extraction plants it is not suitable for animal consumption except for a very short time, but can be preserved by the method now to be described.

According to my method, the citrus fruit waste,

the waste and dried separately. For this purpose, a hammer mill hasbeen found most satisfactory. The waste is processed until it forms a paste that will flow and is capable of being pumped. As it leaves the mill the paste usually has a moisture content of about 85%.

and ultimately becomes a part of the films that are dried on the surfaces of the drums I5 and I6.

The spacing at the nip between the surfaces of said drums I5 and :IB is so adjusted, as by means of the various adjusting bolts- 2|, 22, 23

and 24, that the films lill and 5| adhering to the surfaces of the drums I5 and I6, respectively, are of the desired thickness and compactness.

Said films 60 and BI are dried during the con- 'drums I5 and I6 and then rotating the-drums inwardly toward each other,the material becomes filmed and packed earlier than is the case when the film is regulated and packed only by the same drier drums-at the nip 25. This is particularly advantageous in the case of liquid and pasty materials that are not particularly coherent and that do not adhere well to heated Y drying surfaces;

' justment between the drier drums themselves By providing for relative ad- This paste'is fed by suitable means into the pockets 4! and 48. Steam of a pressure between 70 to 100lbs. per sq. in. is admitted into the drums I5 and I6 which have glass finished surfaces. The drums I5 and I6 and the rolls and 3|, which latter may or may not be heated, are adjusted so that the film being dried is less than inch thick. The surface speed of the driers I5 and I6 is adjusted to give a drying time of the film not exceeding 12 seconds, preferably between 5 and 10 seconds. The coherent dried and between the auxiliary rolls and the drying drums, and by providing for driving the rolls at different surface speeds from the drums and for the'independentcontrol of thetemperatures of the drums and rolls, the desired uniformity and characteristics of. the films of material formed on the surface of the drier drums can be more readily controlled than in other types of ap paratus.

The above mentioned advantages adapt my drying apparatus particularly for drying sewage disposal plant sludge, milk, various vegetable and fruit juices and pulps and the like. The superior functioning of my drying apparatus makes possible the production of novel products from starting materials of this type. As an example of how, by a proper adjustment of the drying conditions by means of my drying apparatus, a novel product may be obtained the production of a new type of dried citrus food product will be described.

The starting material comprises the waste from the manufacture of canned fruit juices and fruit sections, more particularly, grapefruit.

film scraped off the drums I5 and I6 is disintegrated by the conveyors 52 and 54.

Seven to seven and one-half tons of waste are required for the production of one ton of dry product having a moisture content less than 10% and preferably between 6 and 8%. It, forms uniform, small flakes of a thickness of not more than a few thousandths of an inch which are suitable for use as a cattle feed. This bran-like product may be used dry or it may be made up into a mush with water, which it readily absorbs. This process represents a notableadvance in the art, since pastes prepared from citrus-food,

1. Drying apparatus comprising a pair of horizontally aligned main drying drums definin a nip therebetween, a-spreader roll associated with each drying 'drum above the nip thereof to spread material over the drum surfaces, means for rotating the drums to move their materials receiving surfaces through the nip in a downward di-' rection, means for adjusting the drums horizontally to control the width of the nip therebetween and means to adjust the spreader rolls relative to their-drying drums to gauge the thickness of materials spread on thedrums whereby films of material of controlled thickness are' adapted to be deposited on the drums by the spreader rolls and compressed in the alps between the drums under controlled pressure.

2. Drying apparatus comprising a pair of horizontally aligned main drying defining a nip ther'ebetween, a spreader roll associated with each drying drum above the nip to spread material over-the drum surfaces, means for rotating the drums to move their materials receiving surfaces through the nip in a downward direction,

means for rotating the spreader rolls to move thereto to form a nip into which material to be dried may be fed, and means for driving said drum and roll in the same surface direction at the nip but with the roll rotating at a slower surface speed to facilitate spreading said material into a continuous uniform film on said drum.

4. The method of drying materials, which comprises feeding the material into the nip between two revolving cylindrical surfaces, rotating said surfaces at different speeds to produce a rubbing and spreading action causing said material to adhere as a film to one of said surfaces and heating said one surface to dry the film thereon.

5. Drying apparatus comprising a pair of heated main drums arranged in adjustable spaced relation with their axes in substantially the same horizontal plane, an auxiliary smaller diameter roll associated with each of said drums, means for adjusting the .distancebetween the surfaces of each drum and its associated auxiliary roll to control the spreading and thickness of the film of material to be dried passing therebetween. means for removing the films of dried material from said drums, means'defining in cooperation with said spreader rolls and with the upper peripheries of said drums pockets in which the material to be dried is received, pluralities of rods extending almost into, respectively, each nip between said drums and rolls, and means for imparting a limited sideway motion to said rods whereby the escape of bubbles from material in the vicinity of said nips is facilitated.

6. Drying apparatus comprising a plurality of main drying drums arranged in adjustable surface spaced relation, smaller diameter rolls mounted above said drums and forming nips therewith, means for adjusting the distance between the surfaces of each drum and its auxiliary roll to control the spreading thickness of the film material to be dried passing therebetween means for removing the films of dried material from said drums-mounted in spaced relation about the upper peripheries of said drums,

means cooperating with said rolls to define pockets above the upper peripheries of said drums into which the material to be dried is received, means for agitating said material in said nips, means for heating said drums above the boiling point of water and means for driving said rolls in the same surface direction at said nip as said drums but at a slower speed than said drums to cause the spreading of said material as continuous films of uniformthickness on the surfaces of said drums.

'1. The method of drying materials which comprises feeding said material into the nip between two revolving cylindrical surfaces in sucha man-' her as to form there an accumulation of said material, continuously agitating said accumula-- tion in such a manner as to remove bubbles from the vicinity of said nips while rotating said surfaces at different speeds to produce a rubbing and spreading action causing said material to a ere as a film to one of said surfaces and heating'said one surface to a temperature above the boiling point of, water to dry the film thereon.

GLEN OVERTON. 

